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Location: About three miles northwest of Monticello, Minn., and 40 miles northwest of the Twin Cities on the banks of the Mississippi River.
Plant Description: Monticello Nuclear Generating Plant is a single unit boiling water reactor. The plant received its operating license from the U.S. Nuclear Regulatory Commission in September 1970. More than 500 people are employed full time at Monticello. Xcel Energy also owns the Prairie Island Nuclear Generating Plant near Red Wing, Minn.
In a boiling water reactor, water flows through the reactor and picks up heat released by the fissioning of uranium atoms. The water boils to steam, which then is directed to the turbine-generator to produce electricity. The reactor core holds 484 fuel assemblies. Each assembly is about 14 feet long and is a square array of individual fuel rods about the diameter of a finger. About every 22 months, the plant is shut down and one-third of the used fuel assemblies are removed from the core and replaced with new ones. The term “cycle” refers to the 22-month period of operation between refuelings.
Generating Capacity: 600 megawatts, enough electricity to serve about 500,000 homes.
The plant received a 40-year operating license from the federal Nuclear Regulatory Commission in 1970, and it began commercial operation in 1971. In 2006, the NRC renewed the Monticello plant’s license for 20 years, which will allow operations until 2030.
Monticello is among Xcel Energy’s lowest-cost sources of generation on a per megawatt-hour basis, and it does not produce any greenhouse gas emissions.
The plant runs essentially 24 hours a day, seven days per week, except during refueling outages, which occur approximately every 24 months and last about four to six weeks. The plant is highly reliable with a five-year average capacity factor of 83.9 percent from 2005 – 2009. (Capacity factor is the ratio of a power plant’s actual output over a period of time and its output if it had operated at full capacity the entire time.)
Spent Fuel Storage
When used fuel is moved from the reactor, it is stored in a pool inside the plant. In the 1980s, Monticello shipped 1,058 spent fuel assemblies to a General Electric facility in Illinois. Monticello safely built a dry cask storage facility in 2007 - 2008. Ten canisters, each holding 61 fuel assemblies, were safely transferred to the concrete storage bunkers in the fall of 2008.
In fall 2004, the Xcel Energy's board of directors authorized pursuing license renewal for up to 20 years for the Monticello and Prairie Island plants. The NRC renewed Monticello’s operating license in late 2006, allowing that plant to operate for an additional 20 years to 2030.
In June, 2011, the Nuclear Regulatory Commission granted renewed operating licenses for Prairie Island units 1 and 2 for 20 years. The original licenses were set to expire in 2013 and 2014.
Extended Power Uprate
Monticello completed a nine-year process of virtually rebuilding the its plant to increase its generation from 600 to 671 megawatts. Major equipment was installed during the refueling/uprate outages in 2009, 2011 and 2013.
The major components included a high pressure turbine rotor, reactor steam dryer, condensate demineralizer System, 13.8kV System with new transformers powering feedwater pumps and motors, condensate pumps and motors, new feedwater heaters and new heat exchangers. The final pieces of equipment were replaced in the 2013 outage in which more than 3,000 workers were on site to complete the work.
Life cycle manager upgrades included a new main transformer and generator rewind – both original equipment when the plant was commissioned for operation in 1971, a 40-year run.
The Prairie Island and Monticello nuclear generating plants help Xcel Energy avoid producing hundreds of millions of tons of greenhouse gases or emissions, compared to fossil-fueled base-load power plants.
We have speakers on nuclear power available through our Speakers' Bureau.
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